1. Prior Art
In electrohydraulic systems such as adjustable shock absorbers, active suspension systems, variable power steering systems and other high pressure fluid operating systems, the control valves were large in size. This was necessary in order to package the parts necessary to control the high pressure fluid and to operate within the required operating times. Such valves often required maintenance at frequent intervals to replace seals to stop leakage. In those systems where the pressure fluctuated, the response time of the valve also fluctuated.
Presently, valves capable of operating at fast response times in an environment of a variety of pressures, are very large and require considerable power to operate. This is due in part to the massiveness of the several parts making up the valve. In addition, pressure-unbalanced valves cannot normally develop enough magnetic force to operate at high pressures. In order to provide a pressure balanced valve, a sleeve valve may be used, but this requires very tight manufacturing tolerances and is subject to dirt. In such valves, viscous drag substantially slows down the operation time and valve leakage is inherent. Various other methods of balancing pressure and sealing have been used. Bellows, diaphragms and sliding resilient seals are common. However, these all require extra components. In addition, the durability of these sealing mechanisms limits their use. Also, the presence of these mechanisms adversely affects the dynamic operation of the valves.
2. Summary of the Invention
A high pressure, fast response, pressure balanced solenoid control valve having a housing with an open end and an axially extending tubular passageway terminating in a fluid discharge opening. The housing has an outlet pressure passageway axially extending from a position near the fluid discharge opening to a point intermediate the ends of the housing. A valve seat is located in the passageway adjacent to the opening.
A spherical valve member is axially in line with the valve seat and mates therewith in a conical seat. The spherical valve member has a post extending in an axial direction away from the valve seat. A guide bearing means is positioned in the tubular passageway and axially aligned with the valve seat.
A pressure balancing bearing is located in the guide bearing means for relative axial movement therewith and forms a valve and an armature cavity. The bearing supports the spherical valve member post in a sealed manner.
An armature means is spaced in the armature cavity and aligned with the pressure balancing bearing and is moveable therewith. A spacer means spaces the guide bearing means from a solenoid means. The spacing means is positioned at the interior end of the outlet pressure passageway to provide fluid communication between the armature cavity and the outlet pressure passageway and to provide a gap between a stator means and the armature means when the solenoid means is energized.
A high pressure inlet means is in fluid communication with the valve cavity. High pressure fluid enters into the valve housing through the inlet means and fills up the valve cavity. The pressure of the fluid bears against the pressure balancing bearing and against the inside of the valve element. Since force is a function of pressure and area, the force against the valve cavity sides of both the pressure balancing bearing and the valve element is a function of the cross-sectional area of each of them. In the present invention these cross-sectional areas are equal.
In a similar manner, due to outlet pressure passageway, the pressures in the armature cavity and the pressure downstream of the control valve are equal and since the cross-sectional areas are equal, the fluid pressure does not bias the valve element. A bias spring between a fixed stop in the valve cavity and the valve element holds the valve normally closed.
It is a principal advantage of the present invention to provide a high pressure valve having balanced pressures operating on the valve element and the armature allowing high speed operation.
It is another advantage of the present invention to provide a positive sealing valve with the use of a spherical valve-conical valve seat design.
It is yet another advantage of the present invention to operate the valve in a system independently of the pressures found in the system.
It is yet still another advantage of the present invention to have a solenoid operated control valve operate in a high pressure environment and still be a high speed operation with a fast response time.
Many other objects and purposes of the invention will be clear from the following detailed description of the drawings.